In the handling of suspensions or slurries, particularly sewage sludge or other flocculated or unflocculated slurries, it is often necessary to separate the liquid from the solid component of the suspension. For effective liquid-solid separation, devices such as belt filters and belt filter presses are employed.
A suspension is deposited on one end of a belt filter in an area of an apparatus commonly referred to as the "gravity drainage zone" or "gravity section". The belt can be supported by rollers or by perforated plates. Devices enhancing drainage or flow breaker devices are employed to enhance dewatering in the gravity section. Typical arrangements on a nominal two meter sized unit involve approximately ten rows of devices with about eight or nine devices per row. This ensures that all of the sludge in the gravity drainage zone contacts the devices for achieving maximum drainage of free water.
Without devices enhancing drainage or flow breakers, the solid components of the suspension may settle on the belt such that water can not pass by gravity through the belt. The stratified liquid and solid components then exit the zone without being effectively separated. Flow deflectors or similar devices are disclosed in U.S. Pat. No. 4,456,530 to Eustacchio et al. U.S. Pat. No. 3,984,329 to Wenzel et al, U.S. Pat. No. 4,602,998 to Goron and U.S. Pat. No. 4,609,467 to Morales.
By use of suitable flow breakers, the slurry blanket is split and the solid component is pushed aside exposing filter media cleared of slurry or solid material. Openings generated by such flow breakers within the solid component expose the belt to the free water and enable the free water to pass through the belt for collection below the filter belt. The solid component is then separately collected and discharged at an end of the filter belt opposite its inlet for downstream dewatering operations.
The systems disclosed in some of the above cited patents employ upright elongated members of cylindrical or wedge shape as flow breakers for breaking or splitting the slurry. The conventional flow breakers are pivoted or lifted in directions away from the filter belt by relatively complex mechanisms which are relatively difficult and expensive to manufacture and maintain. Additionally, conventional flow breakers interrupt or deflect the slurry, rather than gently turning the slurry upside down.